Behaviours of barges, pattern of movement and thier efficiency, in the port of Yokohama, have been studied.
　The findings of our study are as follows:
　1) Cargo, which carried by barges, are mainly general cargo and 48% are import cargo and 36% are export cargo.
　2) The average tonnage of barges is 221.4 ton, the average operation is 3.7 Rounds/Month and the average of work-days are 16 Day/Month, and the smaller barges work better the larger.
　3) According the O-D Analysis, the main flows of cargo have either their origin or destination, or both, in Honmoku or Yamashita Pier, and 54% of import cargo and 85% of export cargo are handled to and from ships bringing alongside the quays.
　In the other words, cargo handling for ships mooring on bouys is not the primal function of barges in the port of Yokohama.